1. Field of the Invention
The present invention relates to dual pressure relief valves and more particularly to a selector valve permitting the operator to switch the pressure being monitored from one relief valve to the other.
In many process industries it is highly desirable to provide dual fluid pressure relief valves in which one valve monitors the fluid pressure while the other pressure is shutoff from the other relief valve. In the event of over pressure blowing the relief valve in operation, that valve may be isolated by switching the fluid pressure to the other relief valve permitting the ruptured valve to be removed or reset.
This invention provides dual relief valves for a fluid pressure system.
2. Description of the Prior Art
It has been common practice to provide dual relief valves for fluid process systems by connecting two relief valves in parallel with a fluid process line in which the outlets of the relief valves are connected in common with a discharge header. Each of the relief valves is provided with an upstream and a downstream fluid shutoff valve to isolate the respective relief valve when its seal fails or needs servicing or testing.
One known selector valve for directing fluid to one or the other of a pair of fluid relief valves features a rotor which includes a stop member interrupting flow to one of the relief valves which must be unseated and then rotated 180.degree. with the rotor to axially position and seat the stop member over the fluid passageway to the ruptured valve.
This invention uses flap valves disclosed in U.S. Pat. No. 3,066,693 issued Dec. 4, 1962 to Taylor for Float Valve For Drill Pipe And The Like. This invention is distinctive over known prior art by providing a Y-shaped deverter body interposed in a fluid flow line having a relief valve connected with the respective leg of the Y-shape and opened and closed by a flap valve respectively movable to a closed or open position by a pinion driven rack for closing one flap valve and simultaneously allowing the opposite spring urged flap valve to be biased to an open position.